[time-nuts] HP53132A vs SR625

Magnus Danielson magnus at rubidium.dyndns.org
Sun Mar 17 07:45:59 EDT 2013

On 03/17/2013 01:43 AM, Bob Camp wrote:
> Hi
> The 53132 is indeed a fine counter. It's got another flaw though - right at 10 MHz the resolution takes a dive. If you are doing time nut stuff, that may be a significant issue.

The frequency averaging method can make use of the beating of the 
reference clock against the incomming clock, to get more information on 
the frequency difference. If the clocks are near each other, it takes 
longer averaging to get the same effective resolution. You can expect 
the same type of effect around frequency ratios like 3/2 etc.

This is expected as it is a systematic effect where most of the new 
samples does not bring any new info as they pop in systematically in the 
places where they don't give info. Adding noise (sloppy trigger) could 
actually improve the precission, as it would combat the quantization effect.


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